Electrical heater.



F. KUHN. ELECTRICAL HEATER.

APPLICATION FILED NOV. 2|. I9I4.

-1,15.|,4=17. Patentedspt. 21, 1915.

WHT/58858.' NVENTR w/fm dfI/ y W111i MM 9mm Mw 1 zum A TTOR/VEKS' UNITED STATES FRANK KUHN, OF DETROIT, MICHIGAN.

ELECTRICAL HEATER Specication of Letters Patent.

Patented sept. 21, 1915.

Application filed November 21, 1914. Serial No. 873,294.

To all l0/10m t m ay concern.'

Be it known that I, FRANK KUHN, a, citizen of the United States of America, residing at Detroit, in the county of Vayne and State of Michigan, have invented certain new and useful Improvements in Electrical Heaters, of which the following is a specification, reference being had therein to the accompanying drawings.`

The invention relates to electrical heaters of that type in which the heat is dissipated from a naked resistor.

It is the particular object of the invention to guard the resistor so as to avoid danger of short circuiting, and at the same time to obtain a construction which is inexpensive to manufacture and etlicient in its operation.

In the drawings: Figure 1 is an elevation of a portion of the heater; Fig. 2 is a cross section on line ar-x Fig. l; Fig. 3 is a perspective view of one of the supporting brackets showing the insulator spools in engagement therewith but with the metallic guard removed; and Fig. 4 is a longitudinal section showing two adjacent spools with a section of the metallic guard extending therebetween.

A is a suitable support, preferably formed of metallic bars and which may be attached to any suitable supporting frame (not shown).

B are bracket members attached to the bars A, and which hold insulator spools C. These brackets may be formed of narrow strips of metal spot-welded or otherwise attached to the bars A, and having their opposite end portions bent to embrace grooves C in adjacent spools C. The brackets are arranged in series along the bars A so as to space the spools C a proper distance for supporting the resistor D. This resistor, as shown is in the form of a coil extending through the alined spools and at the end of the series bent into a loop D for engagement with the spools of the parallel bar.

To guard the resistor from accidental contact and short circuiting I provide guards E which extend between adjacent alined spools. These guards E may be formed either of open spirals of wire, as shown at E, or by perforated sheet metal tubes, as indicated at E. The opposite ends of the guards are supported by the spools, preferably by providing projecting portions F of reduced diameter upon which the ends of the guards are sleeved.

With the construction as described it will be observed that in the normal position of parts each of the guards is spaced from the resistor so as to be out of electrical contact therewith, while the openings in the guard will permit of radiation of the heat as well as convection of air currents. It will further be observed that each of the guards is insulated from all of the other guards so that in case of accidental contact between some portion of the resistor and the surrounding guard section this will not cause a burn-out of the circuit. In fact, the length of the resistor inclosed by any one guard section is so short that there is but slight difference of potential between the opposite ends, so that even in case the resistor should be in contact with the guard at separated points no damage would result.

The construction is one which may be` manufactured at low cost and may be built up into units of any desired size or capacity.

What I claim as my invention is l. An electrical heater, comprising an alined series of insulator spools, a resistor extending through said series and supported thereby, the diderence of potential between the ends of the resistor between adjacent spools being slight, and a plurality of guards surrounding the resistor, extending between adjacent insulator spools and supported thereby, to be insulated from each other.

2. In an electrical heater, the combination with a series of alined insulator spools, of a resistor threaded through said spools and supported thereby, and a plurality of open guards surrounding said resistor, extending between adjacent spools and supported thereby so as to be insulated from the resistor and each other, the resistance of the resistor between adjacent spools being slight, thereby producing a slight difference of potential between the ends of the resistor between said spools.

3. In an electrical heater, the combination with a series of insulator spools, of a resistor threaded through said spools and supported thereby, and a plurality of open guards surrounding sections of the resistor, concentric therewith and extending between adjacent spools, the ends of said guards being seated upon said spools to be supported thereby, the difference of potential between the ends of the sections of the resistor surrounded by said guards being slight.

4. In an electrical heater, the combination with a series of insulator spools, of a resistor threaded .through said spools and directly supported thereby, a guard surrounding said resistor'extending between adjacent spools, the difference of potential between the ends ofthe resistor surrounded by said guard being slight, and projections on said spools upon which the ends of said guard are sleeved and supported.

5. In an electrical heater, the combination with a supportin bar, of a series of insulator spools, Vbrac ets attached to said supporting bar and bent to embracesaid spools, a resistor threaded through said\spools, an open guard surrounding said resistor extending between adjacent spools, and lugs projecting from the ends of said spools-'upon which the ends of said guard are sleeved.

6. In an electrical heater, the combination of a supporting bar, a series of bifurcated brackets attached thereto, pairs of insulated spools embraced by said brackets, each spool being provided with projecting lugs at its opposite ends of reduce-d diameter, a resistor threaded through one alined series of spools and return bent and threaded through the parallel line of spools, and se arate guard sections extending between a inedl spools, said guard sections being concentric with and spaced from the resistor and sleeved upon the portions of said spools of reduced diameter.

7. In an electrical heater, the combination with two parallel series of insulator spools, of a means for centrally supporting pairs of opposite spools in the two series, a resistor threaded t rough said spools, projections on said spools, and a perforated tube surrounding said resistor extending between adjacent spools and supported by said projections.

8. In an electrical heater, the combination with a series of insulator spools,- of a resistor threaded therethrough, projections on each end of said spools, and a perforated tube extending between adjacent spools and engaging the projections thereon.

In testimony whereof I affix my signature in presence of two witnesses.

FRANK KUHN.

Witnesses:

ARGHLE OAKES, C. H.' REUTELSTERZ. 

